lib/libc_r/uthread/uthread_fork.c

   1 /*
   2  * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by John Birrell.
  16  * 4. Neither the name of the author nor the names of any co-contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * $FreeBSD: src/lib/libc_r/uthread/uthread_fork.c,v 1.19.2.7 2002/10/22 14:44:03 fjoe Exp $
  33  */
  34 #include <errno.h>
  35 #include <string.h>
  36 #include <stdlib.h>
  37 #include <unistd.h>
  38 #include <fcntl.h>
  39 #include <pthread.h>
  40 #include "pthread_private.h"
  41
  42 pid_t
  43 _fork(void)
  44 {
  45         struct pthread  *curthread = _get_curthread();
  46         int             i, flags;
  47         pid_t           ret;
  48         pthread_t       pthread;
  49         pthread_t       pthread_save;
  50
  51         /*
  52          * Defer signals to protect the scheduling queues from access
  53          * by the signal handler:
  54          */
  55         _thread_kern_sig_defer();
  56
  57         /* Fork a new process: */
  58         if ((ret = __sys_fork()) != 0) {
  59                 /* Parent process or error. Nothing to do here. */
  60         } else {
  61                 /* Close the pthread kernel pipe: */
  62                 __sys_close(_thread_kern_pipe[0]);
  63                 __sys_close(_thread_kern_pipe[1]);
  64
  65                 /* Reset signals pending for the running thread: */
  66                 sigemptyset(&curthread->sigpend);
  67
  68                 /*
  69                  * Create a pipe that is written to by the signal handler to
  70                  * prevent signals being missed in calls to
  71                  * __sys_select:
  72                  */
  73                 if (__sys_pipe(_thread_kern_pipe) != 0) {
  74                         /* Cannot create pipe, so abort: */
  75                         PANIC("Cannot create pthread kernel pipe for forked process");
  76                 }
  77                 /* Get the flags for the read pipe: */
  78                 else if ((flags = __sys_fcntl(_thread_kern_pipe[0], F_GETFL, NULL)) == -1) {
  79                         /* Abort this application: */
  80                         abort();
  81                 }
  82                 /* Make the read pipe non-blocking: */
  83                 else if (__sys_fcntl(_thread_kern_pipe[0], F_SETFL, flags | O_NONBLOCK) == -1) {
  84                         /* Abort this application: */
  85                         abort();
  86                 }
  87                 /* Get the flags for the write pipe: */
  88                 else if ((flags = __sys_fcntl(_thread_kern_pipe[1], F_GETFL, NULL)) == -1) {
  89                         /* Abort this application: */
  90                         abort();
  91                 }
  92                 /* Make the write pipe non-blocking: */
  93                 else if (__sys_fcntl(_thread_kern_pipe[1], F_SETFL, flags | O_NONBLOCK) == -1) {
  94                         /* Abort this application: */
  95                         abort();
  96                 }
  97                 /* Reinitialize the GC mutex: */
  98                 else if (_mutex_reinit(&_gc_mutex) != 0) {
  99                         /* Abort this application: */
 100                         PANIC("Cannot initialize GC mutex for forked process");
 101                 }
 102                 /* Reinitialize the GC condition variable: */
 103                 else if (_cond_reinit(&_gc_cond) != 0) {
 104                         /* Abort this application: */
 105                         PANIC("Cannot initialize GC condvar for forked process");
 106                 }
 107                 /* Initialize the ready queue: */
 108                 else if (_pq_init(&_readyq) != 0) {
 109                         /* Abort this application: */
 110                         PANIC("Cannot initialize priority ready queue.");
 111                 } else {
 112                         /*
 113                          * Enter a loop to remove all threads other than
 114                          * the running thread from the thread list:
 115                          */
 116                         pthread = TAILQ_FIRST(&_thread_list);
 117                         while (pthread != NULL) {
 118                                 /* Save the thread to be freed: */
 119                                 pthread_save = pthread;
 120
 121                                 /*
 122                                  * Advance to the next thread before
 123                                  * destroying the current thread:
 124                                  */
 125                                 pthread = TAILQ_NEXT(pthread, tle);
 126
 127                                 /* Make sure this isn't the running thread: */
 128                                 if (pthread_save != curthread) {
 129                                         /* Remove this thread from the list: */
 130                                         TAILQ_REMOVE(&_thread_list,
 131                                             pthread_save, tle);
 132
 133                                         if (pthread_save->attr.stackaddr_attr ==
 134                                             NULL && pthread_save->stack != NULL) {
 135                                                 if (pthread_save->attr.stacksize_attr
 136                                                     == PTHREAD_STACK_DEFAULT) {
 137                                                         /*
 138                                                          * Default-size stack.
 139                                                          * Cache it:
 140                                                          */
 141                                                         struct stack    *spare_stack;
 142
 143                                                         spare_stack
 144                                                             = (pthread_save->stack
 145                                                             + PTHREAD_STACK_DEFAULT
 146                                                             - sizeof(struct stack));
 147                                                         SLIST_INSERT_HEAD(&_stackq,
 148                                                             spare_stack, qe);
 149                                                 } else
 150                                                         /*
 151                                                          * Free the stack of
 152                                                          * the dead thread:
 153                                                          */
 154                                                         free(pthread_save->stack);
 155                                         }
 156
 157                                         if (pthread_save->specific_data != NULL)
 158                                                 free(pthread_save->specific_data);
 159
 160                                         if (pthread_save->poll_data.fds != NULL)
 161                                                 free(pthread_save->poll_data.fds);
 162
 163                                         free(pthread_save);
 164                                 }
 165                         }
 166
 167                         /* Treat the current thread as the initial thread: */
 168                         _thread_initial = curthread;
 169
 170                         /* Re-init the dead thread list: */
 171                         TAILQ_INIT(&_dead_list);
 172
 173                         /* Re-init the waiting and work queues. */
 174                         TAILQ_INIT(&_waitingq);
 175                         TAILQ_INIT(&_workq);
 176
 177                         /* Re-init the threads mutex queue: */
 178                         TAILQ_INIT(&curthread->mutexq);
 179
 180                         /* No spinlocks yet: */
 181                         _spinblock_count = 0;
 182
 183                         /* Don't queue signals yet: */
 184                         _queue_signals = 0;
 185
 186                         /* Initialize the scheduling switch hook routine: */
 187                         _sched_switch_hook = NULL;
 188
 189                         /* Clear out any locks in the file descriptor table: */
 190                         for (i = 0; i < _thread_dtablesize; i++) {
 191                                 if (_thread_fd_table[i] != NULL) {
 192                                         /* Initialise the file locks: */
 193                                         memset(&_thread_fd_table[i]->lock, 0,
 194                                             sizeof(_thread_fd_table[i]->lock));
 195                                         _thread_fd_table[i]->r_owner = NULL;
 196                                         _thread_fd_table[i]->w_owner = NULL;
 197                                         _thread_fd_table[i]->r_fname = NULL;
 198                                         _thread_fd_table[i]->w_fname = NULL;
 199                                         _thread_fd_table[i]->r_lineno = 0;;
 200                                         _thread_fd_table[i]->w_lineno = 0;;
 201                                         _thread_fd_table[i]->r_lockcount = 0;;
 202                                         _thread_fd_table[i]->w_lockcount = 0;;
 203
 204                                         /* Initialise the read/write queues: */
 205                                         TAILQ_INIT(&_thread_fd_table[i]->r_queue);
 206                                         TAILQ_INIT(&_thread_fd_table[i]->w_queue);
 207                                 }
 208                         }
 209                 }
 210         }
 211
 212         /*
 213          * Undefer and handle pending signals, yielding if necessary:
 214          */
 215         _thread_kern_sig_undefer();
 216
 217         /* Return the process ID: */
 218         return (ret);
 219 }
 220
 221 __strong_reference(_fork, fork);